The invention relates to a vehicle with a drive engine for driving a traction drive and for driving at least one working hydraulic system.
In the case of machines or utility vehicles, it is the norm that only one prime mover is provided, with which the different consumers of the vehicle are driven. In particular, it is usual to provide a single diesel engine. In the case of several different functions, for example a traction drive as well as an additional working hydraulic system, the power produced by the diesel engine is branched. A portion of the available overall power of the diesel combustion engine is allotted to the respective consumers in this case according to a defined control strategy. If short-term peak loads occur, this results for example in a reduction in the engine speed. Utility vehicles and construction machinery, such as fork lift trucks, wheel-type loaders or even refuse vehicles are frequently accelerated to low velocities and then braked to a stop again. At the same time or in the traction intervals occurring, work is carried out using the working hydraulic system. To be able to use the energy released in the braking process, it is known from DE 32 35 825 A1 to provide a device for storing energy.
On the vehicle known from DE 32 35 825 A1, a prime mover is connected to a drive axle via a characteristics converter. The power take-off shaft of the prime mover is coupled to an auxiliary drive, which is connected to a working hydraulic system via a clutch and an overrunning clutch. A hydromachine can be coupled to the working hydraulic system via a further clutch, this hydromachine being connected via a line to an accumulator. Due to this, when the corresponding clutches are closed, the hydromachine can convert the kinetic energy of the vehicle into storable pressure energy in overrunning of the vehicle. If the accumulator is to be recharged without overrunning occurring, driving of the hydromachine indirectly via the auxiliary drive and the clutches is also possible.
In the case of the proposed vehicle, it is disadvantageous that the hydromachine has to be activated in a complex manner via a branching gearbox as well as at least one clutch. This not only increases the losses when storing energy, so that only a portion of the braking energy can be stored in the accumulator, but also increases the losses again when recovering the stored energy. At any rate, it is necessary to carry the working hydraulic system along also when recovering the energy, due to which considerable losses arise in spite of the working hydraulic system not being used. In an alternative execution, a coupling with the drive axle of the vehicle can be produced, bypassing the working device. However, an additional transfer gearbox is necessary in this case to achieve speed matching of the hydromachine.